Hochu-ekki-to, a multiple herbal drug which consists of 10 medicinal plants (Astragali radix, Atractylodis lanceae rhizoma, Ginseng radix, Angelicae radix, Bupleuri radix, Zizyphi fructus, Aurantii nobilis pericarpium, Glycyrrhizae radix, Cimicifugae rhizoma, and Zingiberis rhizoma), was administered to 38 patients with asymptomatic methicillin-resistant Staphylococcus aureus (MRSA) bacteriuria, and the effect was evaluated. The patients received Hochu-ekki-to at a daily dose of 7.5 g for at least 24 weeks. As a prognostic nutritional index (PNI), albumin and lymphocytes in the peripheral blood were measured, in addition to urine culture. The results were compared with those in 12 untreated control patients with asymptomatic MRSA bacteriuria. Four of the 38 patients treated with Hochu-ekki-to received antibacterial drugs during the treatment period, and were excluded from the study. Among the 34 eligible patients treated with Hochu-ekki-to, urinary MRSA was eradicated in 12 patients, and the bacterial counts in urine culture decreased to 102 CFU/ml or less in 10 patients. In patients treated with Hochu-ekki-to, urinary bacteria were decreased from 10 weeks after treatment compared with the findings in control patients (P < 0.05). PNI improved in all patients compared with the baseline before treatment. It was considered that the biodefense function was recovered via nutritional improvement by the administration of Hochu-ekki-to, and, as a result, MRSA bacteriuria improved. Further investigation would be needed in future.